Q: I am a working mom with three kids. The only time I can get to the gym is at lunch. How can I maximize my workouts in 45 minutes to get the best benefits since I have limited time?

A: Like yourself, most people don’t get lengthy lunch breaks that allow time for prolonged workouts plus travel to the gym, showering and getting back to your desk — oh, and grabbing some food, too.

But you can use your lunch hour to get in a good, albeit quick, workout, says personal trainer Nicki Anderson, a spokesperson for the IDEA Health and Fitness Association and owner of Reality Fitness, a personal training studio in the Chicago area.

“To get the biggest bang for your buck, the key word is intensity,” Anderson says.

One of the biggest mistakes women make at the gym, she says, is thinking their available workout time is best spent doing all cardio — often at the same pace the entire time. Rather than doing 45 minutes of cardio at a steady — and probably a relatively easy — pace, you’ll get better overall results by doing less but more intense cardio and also incorporating some strength exercises, Anderson says.

With 45 minutes to work out, she recommends dividing your time between cardio and strength-training, while allowing some time at the beginning and end for a short warm-up and cool-down.

For the cardio portion, aim for high-intensity interval training on a treadmill or bike, for instance, at 65 percent to 75 percent of your maximum heart rate, says Anderson. Work at that pace for three to five minutes, then lower the intensity to allow yourself to recover briefly, and then go for another high-intensity burst. As your fitness level improves with time, you can try to push yourself harder.

Climb out of your fitness rutWhen hitting the weights for only about 20 minutes, you may not have enough time to work all the major muscle groups in one day. So target a few muscle groups, such as chest, back, shoulders and abs one day, and then other groups, such as triceps, biceps and legs, on another.

For people who have just 30 minutes to work out during lunch, which may be more realistic for many, one approach that can work is to do cardio one day, weights the next, then cardio, etc., says Anderson. This way, you’re training regimen is well rounded, even if you can’t do everything on one day.

Above all, make the most of whatever time you do have to work out, even if it’s not as much as you’d like. “Don’t get into the mindset that it’s all or nothing,” says Anderson.

And on hectic days when a lunchtime trip to the gym just isn’t happening, even squeezing in a 15-minute walk helps. “Whatever you can do is brilliant,” she says.

Q1: I'm really confused — should I eat before a workout or after? I have researched this and got both answers. So please, which is best?

Q2: If I'm getting out of bed and doing a 30-minute cardio routine on my elliptical, do I need to eat anything beforehand?

A: There are good reasons to eat before and after exercise, but there aren’t strict nutritional rules that apply across the board to everyone, says Molly Kimball, a sports dietitian at Ochsner Clinic's Elmwood Fitness Center in New Orleans.

Factors that can determine whether you should eat before and/or after exercise include when you last ate, how you’re feeling, the intensity and duration of your workout, and the timing of your other workouts.

Not everyone feels like eating just before exercise, and that’s generally fine for recreational exercisers, says Kimball, even if you’re exercising first thing in the morning like the reader in the second question. “Your body has enough carbohydrate reserves to fuel exercise lasting up to 60 to 90 minutes,” she says. “So if you prefer to exercise on an empty stomach, that's completely acceptable, as long as it's a shorter workout, and your energy is strong during your workout.”

But she notes that some people may find that a snack half an hour before a workout boosts their performance. “Experiment with eating a combination of carbohydrate and protein beforehand,” she says. “You may be surprised at how much more power and endurance you have during your workouts.”

one ounce of 2 percent or low-fat cheese with a serving of whole-grain crackers

fresh fruit with Greek yogurt or cottage cheese.

If you’re planning to exercise following a heavy meal, wait about two hours so you don’t start your workout with a very full stomach, she advises.

As for eating right after exercise, it’s not absolutely necessary for average exercisers doing typical workouts. But if you’re starving or it’s mealtime — for instance, if you’ve just finished a lunchtime workout, as discussed in the reader question above — go ahead and eat.

Eating shortly after exercise is most necessary for athletes in training, says Kimball. “Refueling after workouts is especially important if you're training twice daily (such as for a triathlon), or if you train hard on multiple days,” she says. “This recovery fueling should ideally be within the first 20 to 30 minutes after you finish exercising, when your muscle cells are most sensitive to glycogen [carbohydrate] replenishment.”

Kimball says some good post-workout, high-carb snacks that can aid muscle recovery include:

a glass of low-fat chocolate milk

a bowl of whole grain cereal with skim or low-fat milk

Ultimately, listen to your body to guide your eating habits before and after exercise, says Kimball. “If eating prior to any workout helps your energy and power, then have a snack, no matter the intensity or duration of your workout,” she says. “And if you know that eating after any workout will prevent you from feeling weak, shaky or ravenous, then by all means, refuel after exercising.”